Refrigerator door opener



Nov. 28, 1967 E. J. MOORMAN ETAL 3,354,583

REFRIGERATOR DOOR OPENER Filed Sept. 27, 1965 5 Sheets-Sheet l INVENTORS Ear! J. Moorman Floyd ogoody Their Attorney E. J. MOORMAN ETAL 3,354,583

Nov. 28, 1967 REFR IGERATOR DOOR OPENER 5 Sheets-Sheet 2 Filed Sept. 27, 1965 INVENTORS Y Z Wm M Mm r Fig. 2

Their Attorney Nov. 28, 1967 Filed Sept. 27, 1965 E. J. MOORMAN ETAL REFRIGERATOR DOOR OPENER 5 Sheets$heet 4 INVENTORS Earl J.Moorman Floyd 0.0od 1% Their Attorney- Nov. 28, 1967 v E. J. MOORMAN ETAL 3,

REFRIGERATOR DOOR OPENER Filed Sept. 27, 1965 5 Sheets-Sheet 5 96 L2 T I |2| 98 INVENTORS Earl J.Moorman Floyd 0%od:

Their Afforne y United; States Fatent 3,354,583 REFRIGERATOR DOOR OPENER Earl J. Moorman and Floyd 0. Moody, Dayton, Ohio, as-

signors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Sept.'27, 1965, Ser. No. 490,194 4 Claims. (Cl. 49-276) ABSTRACT OF THE DISCLOSURE This invention pertains to refrigerating apparatus and more particularly to electrical means for opening the door of a refrigerator cabinet and similar doors.

Theme of magnetic door seals on refrigerator door cabinets has made the doors more diflicult to open especially when the magnetic seals are completely effective to prevent any leakage of air into the cabinet. Under such circumstances, the warm air which flows into the cabinetwhen the debris opened will become cool after the air has been sealed in by the closing of the door. The cooling of this air causes it to contract and create a vacuum= in the interior of the cabinet which greatly increases the force required to open the door. This force amounts to the difference between theatmospheric pressure on the outer surface of'the door and the vacuum or less than'atrhospheric pressure within thecabinetJ Since the door presents a comparatively large area, a dillerence of only one pound per square inch' can provide a con- 's'iderable force effective to holdthe door tightly in a closed position. Not' only is it necessary to overcome this closing force due to the difi'erence in air pressures on the doOr,-but--it'is also-necessary to overcome the closing force of the magnetic said.

" -It 'is an object of this invention'to provide a simple electrically operate'cl'means for opening a door.

'It" isanotherobject of this invention to provide a simple electrically operated means having an initially high mechanical advantage for initially forcing open the door until thema gnetic seal is' broken to quickly reducethe pressure differential and themagnetic attraction. Y

It is another object of this invention to provide a simple arrangement-formultiplyingthe force of an electric motor to open a door and to stop the motor in the starting position for -quicklyopening"'the door whenever desired.

Th'ese and other objects are attained in the form shown in the drawings in which an electrical motor provided with an automatic brake is mounted in the door and has a gear reduction with a'rotatable arm. The rotatable arm isno-rmally free of the strike in the stopping position which is controlled by a cam upon the output shaft which opens a switch when the arm reaches the stopping position. The strikdis located"inside the projection of thearm.

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To open the door, a push button switch shunts the stopping switch to start the motor and the rotation of the arm. After a few degrees of rotation of the arm it engages the strike at a small angle which provides an initial mechanical advantage of about 28 to 1 for overcoming the force of the differential in air pressure upon the door as well as the magnetic attraction of the magnetic seal. As the arm rotates, the strike and the angle between the movement of the projection on the arm and the strike increases While the mechanical advantage is reduced so that the door gains suiiicient momentum within the period of the exertion of force between the arm and the strike to carry it to the fully open position by the initial momentum imparted to it. The door is manually closed without any difficulty since the pressures are equalized as soon as the door is opened and the magnetic attraction will assist in pulling the door closed.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown,

In the drawings:

FIGURE 1 is a fragmentary sectional view of a portion of a refrigerator cabinet embodying the electrical motor operated door opener embodying our invention taken along the line 1-1 of FIGURE 2;

FIGURE 2 is a fragmentary sectional view taken along the line 2-2 of FIGURE 1;

FIGURE 3 is a diagram indicating the mechanical advantage and the stroke during the first of rotation of the operating arm;

FIGURE 4 is a transverse vertical sectional view taken along the lines 4-4 of FIGURE 1;

FIGURE 5 is a fragmentary bottom sectional view of the motor taken substantially along the lines 55 of FIGURE 4;

FIGURE 6 is an enlarged side View of the operating arm and its adjustable'connection with the switch cam;

FIGURE 7 is a fragmentary exploded sectional. view taken along the lines ;77 of FIGURE 6; and l FIGURE 8 is a wiringdiagram.

Referring now to the drawings and more particularly to FIGURES 1, 2, 4 and 5 there is indicated the top wall 20 and left side wall 22 and the door 24 of a refrigerator cabinet. The door includes a side member 26 shaped to provide a finger gripping notch 28 up and clown the side thereof, together with an ornamental .sheet metal front 30'extending between the side members. The door around its edges'is provided with a magnetic seal 32 having a bellows type flexible connection 34 with an integral anchor strip 36 fastened to the door by suitable screws 38 and the bracket 40. The magnetic seal 32 extending along the four sides of the door is magnetically attracted to the sheet steel fiange'42 forming a door jamb which surrounds the door opening. The door 24 is provided with an inner pan 44 of suitable sheet plastic which is provided with an enlargement 46 to provide 'a space 48 for accumulation of the electrical motor door opener drive mechanism. The door 24 is also provided .with an inner mounting plate 50 to which is fastened by the fastening members 52, the gear reduction housing 54. Fastened to thegear reduction housing 54 is an electrical motor 56 having an automatic brake 58 on the motor drive shaft 60 which is normally held in engagement with the braking surface 62 by a weak coil spring 64 which urges the motor drive shaft 60 and the brake member 58 to the right to cause the brake 58 to engage the brake surface 62 to stop the motor 56 as soon as it is deenergized.

The motor drive shaft 60 connects through the reduction gearing in the reduction gear case 54 with an output shaft connecting with the cam member 66. This cam member 66 has a cam nose 68 Which normally engages the spring pressed plunger 70 of a switch 72 which is open when the plunger 70 is depressed and closed when the plunger 70 moves upwardly upon its release by the cam nose 68. The switch 72 is also mounted upon the plate 50. The cam member 66 extends through an aperture 74 in the side Wall of the door 44. The cam member 66 is provided with a toothed flange 76 which is adapted to fit in many different selected positions in a complementary toothed recess 78 in the operating arm 80. The operating arm 80 is located between the side of the door pan 44 and the adjacent side wall 22 of the refrigerator cabinet. This operating arm is fastened to the cam member 66 by a screw 82 which threads into the end of the drive shaft 84, connecting to the cam 66. The operating arm 80 is provided with an outwardly extending projection 86 which extends over the strike surface 88 upon a strike member 90 which is mounted upon the front of the side wall 22 as indicated in FIGURES 1 and 2. The projection 86 overhangs a substantial portion of the strike surface 88. The arm 80 is assembled to the cam member 66 in such a position that the projection 86 projects forwardly from the axis of the cam member 66. The strike 90 extends upwardly from the location of the projection 86, a distance greater than the length of the arm 80.

The motor circuit, shown in FIGURE 8, includes a supply conductor L-1 connecting with one terminal of the motor 56 while the second terminal of the motor 56 connects through the conductors 90 and 92 with the stop switch 72 which in turn is connected by the conductor 94 with the second supply conductor L 2. To start the motor 56 to open the door, a push botton 9 6 is closed which closes a shunt circuit comprising a conductor 98 connecting the push button 96 with the conductor 90 and a conductor 121 connecting the push button switch 96 with the supply conductor L-2.This push button switch 96 may be mounted either upon the door or upon any suitable part of the cabinet. The push button switch 96 is movably mounted in a push button holder 123 which is fastened to the front of the door as shown in FIGURE 2. The push button 96. is connected to a switch mechanism 125 which is mounted within the door 24. Upon the closing of the push button switch, the motor 56 rapidly attains full speed and rotates the cam 66 to close the switch 72 withina tenth of a second after which the push button can be released. By its rapid acceleration at the start the motor 56 attains the full operating speed within less than 3 of rotation of the arm 80. This assures that the motor is operating at full speed when the projection 86 initially engages the strike as indicated in the graph of FIGURE 3 by the reference character 127.

As indicated by the dash-dot part of the circle in FIGURE 2 which shows its path, the radially innermost portion of the projection 86 engages the surface of the strike 88 at such a small angle that it has a niev chanical advantage of 28-1 at the initial contact. This provides the needed force to overcome the inertia of the door 24 as well as any pressure differential of the 'air which may exist upon the door 24 and also the force of the magnetic attraction between the magnetic seal 32 and the door jamb 42. The stroke or opening movement of the door at this time is very small because of the small angle of the path ofv movement 87 of the p oje ion 86 r i e. to the surface of the strike 8 at the time and point of initial contact. As shown by the graph at the point 129, after 5 of movement of the arm from the starting position, the mechanical advantage has been reduced to less than 12, while the stroke or opening movement as indicated by the point 131 is only about of an inch. During the next 10 of movement of the arm, the mechanical advantage reduces to less than 6, but the movement of the door 24 away from the door jamb 42 is more than doubled. During this period the movement of the door increases and continues to increase rapidly to give the door 24 suflicient momentum to swing wide open.

The opening of the door with a relative small electric motor is made possible through this arrangement of the projection 86 and the strike 88 whereby a high initial mechanical advantage inherently linked to a very small stroke changes smoothly and rapidly and automatically to a reducing mechanical advantage with an inherently increasing stroke. This is done by one of the simplest of all mechanisms; namely, a simple lever arm against a simple contact surface. The strike member is preferably made of nylon which preferably is also the material of the arm 80 and the cam 66. This material does not require any lubrication and has a very low coetficient friction so that very little of the force of; the motor is lost due to the frictional contact between the projection 86 and the strike surface 88. This also makes the operation very smoothand quiet. Thus, in this very simple way an, electrically operated door opener is provided which is capable of overcoming the inertia of th door as well as any pressure differential which may be applied to the door in addition to'the magnetic attraction of the magnetic seal which is used to hold the door closed.

After the door is opened, it is closed manually without encountering any substantial. resistance, since the door hinges have little friction and since the magnetic attraction of the magnetic seal for the door jamb assists in, the closing of the door. I

While the embodiments of the present invention as herein disclosed, constitute a preferred form, his .to be understood that other forms might be adopted. a

What is claimed is as follows: i

1. In combination, a door jamb means, a door means o p at ng o c s p na d jam m a s, one of said means being provided with a strike surface, the other of said :means being provided with an electric mo r p ovid with a br k means and means fo rendering effective said brake-means when saidmotor iS deenergized, means for starting said motor, and means pe e y aid mot r f r e sag ns' a d strike ur a e for opening said door, said means operated by said motor including a rotatable arm having a projection extend,- ing into overlapping relation with said strikejsur faceand operable connecting means between saidmotor and said arm, said arm having its center of rotation. located to provide an arc of movement intersecting saidstrike sur; face at a small angle to provide a large initial mechanical advantage to increase the initial; force to open the door.

2. A combination as defined, in claim 1- in which said initial mechanical advan age is substantially twentyeight'to one.

3. A combination as defined in claim 1 in which the arm in its startingposition has its projection located on one side of said striking surface and havingits axis of rotation on the opposite side of said striking surface when said door is inits closed position.

4. In combination, a door jamb means, a door means cooperating to close upon said door jamb means, one of said means being provided withla strike surface, ;the other of said means being provided with. an electric motor,.means for. starting said motor, and means .operated by said motor for engaging said strike surface 6 for opening said door, said means operated by said References Cited i i fifiif i i ivihigfi l illii il iviifi afi $1 213 UNITED STATES PATENTS x e n o n s face and operable connecting means between said motor 2490456 12/1949 Nederhlser 318 366 X and said arm, said arm having its center of rotation 2,576,978 12/1951 Sward 292*97 located to provide an arc of movement intersecting said 5 2,898,138 8/1959 Van Noord 292F201 X strike surface at a small angle to provide a large initial mechanical advantage to increase the initial force DAVID WILLIAMOWSKY Prlmm'y Examiner to open the door. I. KARL BELL, Assistant Examiner. 

1. IN COMBINATION, A DOOR JAMB MEANS, A DOOR MEANS COOPERATING TO CLOSE UPON SAID DOOR JAMB MEANS, ONE OF SAID MEANS BEING PROVIDED WITH A STRIKE SURFACE, THE OTHER OF SAID MEANS BEING PROVIDED WITH AN ELECTRIC MOTOR PROVIDED WITH A BRAKE MEANS AND MEANS FOR RENDERING EFFECTIVE SAID BRAKE MEANS WHEN SAID MOTOR IS DEENERGIZED, MEANS FOR STARTING SAID MOTOR, AND MEANS OPERATED BY SAID MOTOR FOR ENGAGING SAID STRIKE SURFACE FOR OPENING SAID DOOR, SAID MEANS OPERATED BY SAID MOTOR INCLUDING A ROTATABLE ARM HAVING A PROJECTION EXTENDING INTO OVERLAPPING RELATION WITH SAID STRIKE SURFACE AND OPERABLE CONNECTING MEANS BETWEEN SAID MOTOR AND SAID ARM, SAID ARM HAVING ITS CENTER OF ROTATION LOCATED TO PROVIDE AN ARC OF MOVEMENT INTERSECTING SAID STRIKE SURFACE AT A SMALL ANGLE TO PROVIDE A LARGE INITIAL MECHANICAL ADVANTAGE TO INCREASE THE INITIAL FORCE OPEN THE DOOR. 